Kevin Farrow at Recoup discusses how combining modulating electric showers with wastewater heat recovery can provide a simple, low-disruption route to improved EPC performance.
It is now possible to improve a property’s EPC rating by installing a modulating Instantaneous Electric Shower (mIES) with a Waste Water Heat Recovery System (WWHRS). When retrofitted to a ‘single bathroom’ property, this combination can improve an EPC score by up to three points; potentially providing an existing property with what it needs to achieve the EPC C goal with a simply applied showering solution. Greater improvements are achievable when using a higher-efficiency vertical WWHRS unit installed with a pump or on the floor below the shower.
Previously, the combination of electric showering and WWHRS was not recognised within SAP or RdSAP, the methodologies used by energy assessors to calculate EPC ratings. However, the introduction of modulating instantaneous electric showers in 2024 enabled the safe and effective use of WWHRS technology with electric showers.
Mira Showers and Recoup working with the Building Research Establishment (BRE), together with the Department for Energy Security and Net Zero (DESNZ), have since assessed the modelling and performance of mIES used in conjunction with both horizontal and vertical WWHRS units for inclusion within the SAP Appendix Q database. As a result, the improvements from these technologies can now be recognised and accurately reflected in EPC calculations for properties.
The benefits for existing social housing
For properties that already have an electric shower, upgrading to a modulating instantaneous electric shower is a straightforward like-for-like replacement. Where a mixer shower is installed, changing to an electric shower has the added benefit of removing hot water demand for showering from the property’s primary water heating system, creating an electric powered, independent showering solution.
Integrating a mIES with a WWHRS is also simple. The cold water supply to the electric shower is diverted through the WWHRS unit before entering the shower. When showering, heat energy is recovered from the shower wastewater that would otherwise go down the drain. Up to 90% of heat energy generated for showering is usually lost. The WWHRS uses the recovered heat energy to preheat cold water that is sent to the shower reducing the energy needed to reach the desired showering temperature. The mIES automatically reduces the electrical power it uses, improving efficiency and saving up to 40% of the energy per shower use.
A key advantage is the ease of installation. WWHRS systems can be retrofitted beneath a bath or integrated within a shower tray, making them suitable for a wide range of existing housing stock. Installation can often be completed as part of planned bathroom refurbishment programmes, avoiding major building works and reducing inconvenience for residents.
This makes the combination of WWHRS and mIES particularly attractive for social housing retrofit programmes. Saving energy, saving money, reducing emissions and unlike many low-carbon technologies, it can be installed with minimal disruption and without major alterations to the home’s heating system or layout.
Low disruption, happy tenants, & property decarbonisation
The low disruption installation is a significant benefit for both landlords and tenants. Installing under an existing bath and upgrading an existing electric shower can be completed in less than a day. Residents can remain in their homes during installation. Once fitted, the technology operates automatically in the background. There is no requirement for behavioural change to achieve the energy savings.
Long-term operation is equally straightforward. WWHRS systems require no user interaction, no apps and no complex controls, and do not change the showering experience. In fact, showering temperatures are stabilised throughout the year. They require no planned maintenance, helping housing providers minimise ongoing management and servicing costs.
The lower energy consumption translates into lower household bills, an important benefit for tenants constantly impacted by rising energy costs. Where housing providers are responsible for utility costs, the reduced energy demand will deliver significant financial savings when introduced across an entire scheme.
Additional savings are also achieved through improved water efficiency. Replacing a traditional mains-pressure mixer shower with a modulating instantaneous electric shower can reduce shower water consumption by over 50%, significantly lowering water charges. This provides a dual benefit, reducing demand for both energy and water while supporting wider sustainability and decarbonisation objectives.
For housing providers seeking practical, scalable and resident-friendly decarbonising retrofit solutions. The combination of modulating instantaneous electric showers and WWHRS offers measurable energy and water savings, minimal disruption during installation, and improved EPC performance, all without adding any complexity for tenants or housing managers.
Kevin Farrow is head of marketing & design at Recoup Energy Solutions